JPH02216153A - Photosensitive composition and pattern forming method - Google Patents

Abstract

PURPOSE:To lessen the film decrease of a coating film after development of a negative type photosensitive compsn. by incorporating a specific arom. azide compd. therein. CONSTITUTION:The title compsn. of the negative type is formed of the arom. azide compd. (A) expressed by formula I and an alkaline soluble high-polymer compd. (B). In the formula, at least either of X, Y denotes 3 to 7C straight chain or branched chain hydrocarbon group and the other denotes H; 4-azide phenyl sulfonic acid 4'-pentyl phenyl ester or the like is usable as the component A. One or more kinds of the condensation reaction product of phenols and formaldehyde and hydroxystyrene polymer {e.g.: poly(4-hydroxystyrene)} are preferably used for the component B.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a photosensitive composition and a pattern forming method, and particularly to a photosensitive composition that is a photoresist (photosensitive corrosion-resistant film forming material) suitable for microfabrication, and a pattern forming method. [Prior Art] Photosensitive compositions are used for various purposes, for example, in the production of semiconductors. Semiconductor devices, especially 1. S.I., V.
In order to improve the performance of semiconductor devices such as LSI,
It is necessary to improve the resolution (fineness) of the processing.4Currently, gtQ (436ri ni) reduction exposure equipment is widely used for exposure. M. In order to improve the image resolution, increase the NA (numerical aperture) of the reduction projection lens, or increase the g
Efforts are being made to shorten the wavelength from the i-line to the i-line (365 II m ). It is technically difficult to increase the former NA without reducing the exposure area. Even if an exposure optical system with a high NA were created, the depth of focus would be shallow, making it impossible to use a simple process using a single-layer resist coating, which would cause practical problems. The latter shortening of the exposure wavelength is quite promising in practice. Of course, even if the wavelength is shortened, the requirements for resists such as high resolution remain the same. Recently, exposure processes using KrF excimer lasers have not been attracting attention even in the short wavelength region. That's K r F
The exposure wavelength of excimer laser is quite short at 248 nm.
In addition, the output is large and the oscillation is stable at the lh level. For example, the Proceedings of the 47th Japan Society of Applied Physics Academic Conference p.
323.29a ZF-2 (1986) using M, P2400 (manufactured by Sibley Japan) as a positive photoresist, and the results of K r F excimer laser exposure have been reported. Also, Proceedings of the 34th Applied Physics Association Lectures, Volume 2, p, 432.30a N
-8 (1,987) as a positive photoresist PM
The results of KrF excimer laser exposure using MA are reported to be crazy.

[Means to solve the problem]

The above purpose is achieved by the following general formula (1), (wherein at least one of X and Y represents a group consisting of a straight or branched hydrocarbon chain having 3 to 7 carbon atoms, and the remainder represents H. A negative photosensitive silk composition characterized by comprising an aromatic azide compound represented by This is achieved by a pattern forming method characterized by comprising the steps of: coating a photosensitive composition containing a compound on a substrate to form a coating film; and forming a predetermined pattern on the coating film. If the 248 nm absorption of negative photoresist is too strong, the absorption of light on the surface of the coating film will be too strong and the pattern after development will become an inverted trapezoid, making it difficult to create a vertical shape or control the width and width. The disadvantage is that it is complicated. If the concentration of the photosensitizer is lowered in order to reduce absorption, the photocrosslinking caused by exposure to light is insufficient, resulting in a large loss of resist film during development, resulting in the problem that a good pattern cannot be obtained. Therefore, we investigated materials for resist 1 that would not cause film loss during development even when using a small amount of photosensitive agent. As a result, it was found that film loss after exposure and development can be suppressed by adding four suitable alkyl groups to the aromatic azide compound. Such alkyl groups are preferably linear or branched hydrocarbon groups having 3 to 7 carbon atoms, such as propyl, butyl, pentyl, and hexyl groups. The exact amount of the azide compound varies depending on the compound's sensitivity characteristics, optical properties, etc., but generally the total amount (
1 to 40% by weight relative to azide compounds and polymer compounds)
It is preferably within a range of approximately 10 to 30% by weight, and more preferably within a range of approximately 10 to 30% by weight. As the polymer compound of the present invention, polymer compounds used in general negative-type resists can be used, but those that are alkali-soluble are particularly preferred, and those that have dry etching resistance are particularly preferred. Many of these polymer compounds have a benzene ring. Examples include condensation reaction products of phenols and formaldehyde such as cresol novolak resin, copolymers containing phenols, hydroxystyrene polymers, copolymers containing hydroxystyrene, and the like.

[Function] According to the present invention, the absorbance at 248 nm of a 1 μm thick coating film can be easily reduced to 1 or less. This is because the photosensitizer can be used at a lower concentration. For example, if a photosensitive composition with an absorbance of 18 is prepared using the azide compound 3,3'-diazide diphenyl sulfone used in conventional negative-working materials,
The amount of photosensitizer is too small to cause sufficient crosslinking even with B light. Therefore, film loss during development becomes large, making this method impractical. The photosensitive composition of the present invention has no problem of film thinning and has a 248n
Light absorption at m can be easily controlled. When the absorbance is 0.3 to 1.5 for a coating film with a thickness of 1 μm, the cross-sectional shape of the coating film after exposure and development is such that its edges are substantially perpendicular to the surface. If the absorbance is less than 0.3, e.g. 0.1
If this is done, the cross-sectional shape of the coating film after exposure and development will be affected by standing waves from the base and deteriorate. On the other hand, if the value exceeds 1.5, for example 1.6, the cross-sectional shape of the coating film described in item 1 becomes an inverted trapezoid, which is not preferable. [Examples] The present invention will be described in detail below using Examples. It should be noted that the following examples are for illustrating the present invention and are not intended to limit the scope of the present invention. Example 1 A photoresist solution having the following composition was prepared. Poly(4-hydroxystyrene) and 4-azidophenylsulfonic acid 4
A photoresist solution was prepared by dissolving '-pentylphenyl ester in cyclohexane in a weight ratio of 100:20. The above resist was spin-coated onto a silicon wafer, and
It was baked at ℃ for 10 minutes to form a coating film with a thickness of 1 μm. This film was processed using a KrF excimer laser (Lambda P
Exposure was performed using hysik, [1) while changing the irradiation amount and irradiation position. The exposed coating film was developed with a 0.95% aqueous solution of tetramethylammonium hydroxide for 135 seconds. By this operation, the coating film in the unexposed areas was removed, and only the coating film insolubilized by exposure remained on the wafer. The film thickness after development was measured using a stylus-type film thickness meter (Alpha Step 200; Tenc).
or Instruments),
Plot that value against exposure. The photosensitive characteristic curve of photoresist was obtained. The photosensitive characteristic curve thus obtained is shown in FIG. From FIG. 1, it can be seen that the photosensitive composition of the present invention has an N reduction of 11
00n, sensitivity sufficiently high for practical use (11mJ/cm”)
It can be seen that it has a contrast characteristic (1°7).
Further, the coating film produced in the same manner as above was exposed to 50 mJ/Cm'' of KrF excimer laser light through a hard mask having a pattern width of 0.5 μm. Developed with a 95% aqueous solution for 135 seconds to obtain a good pattern with a width of 0.5 μm. At this time, the transmittance at a thickness of 17 μm was 25%. Comparative Example 1 4-Azide described in Example 1 Phenylsulfonic acid 4'-
The method of Example 1 was repeated, except that 3°3'-diazidiphenyl sulfone was formulated in place of the pentylphenyl ester, in a weight ratio of OO:6. The resulting photosensitive characteristic curve is shown in FIG. From Figure 1, the rs degree was low (300 mJ/cm2), the contrast was low (0,6), and the film thickness was 480 nm. At this time, the transmittance of 1 μm thickness was 9%, and Example 10
Compared to 25%, the transmittance is low and the characteristics are poor. Comparative Example 2 4-azidophenylsulfonic acid 4'- described in Example 1
The method of Example 1 was repeated except that 4-azidophenylsulfonic acid phenyl ester was formulated in a weight ratio of 100:30 instead of pentylphenyl ester. As a result, the sensitivity was low (31 mJ/cm") and the film loss was as much as 300 nm. This comparative example shows the effectiveness of the alkyl substituent. Example 2 4-azidophenyl described in Example 1 Sulfonic acid 4″
-4-azidobutylsulfonic acid 4' -butylphenyl ester 3.3' instead of pentylphenyl ester
The method of Example 1 was repeated, except that the diazidodiphenyl sulfone was formulated in a weight ratio of 100:30. As a result, the sensitivity was 15 mJ/cm2, the contrast was 2.2, and no film loss occurred. A good pattern with a width of 0.5 μn1 was obtained. Example 3 4-azidophenylsulfonic acid 4'- as described in Example 1
The procedure of Example 1 was repeated, except that instead of pentylphenyl esterification, 4-azidobutylsulfone@4'-propylphenyl ester 3,3'-diazidodiphenylsulfone was formulated in a weight ratio of 100:30. As a result, the sensitivity was 17 mJ/cm", the 5 contrast was 2.2, and no film formation occurred. A good pattern with a width of 0.5 μm was obtained. Example 4 4-Azide described in Example 1 Phenylsulfonic acid 4'-
Instead of pentylphenyl esterification, 4-azidobutylsulfonic acid 2'-4'-dibutylphenyl ester and 3,3'-diazidodiphenylsulfone were added at a ratio of 100:30.
The method of Example 1 was repeated except that the weight ratio of the result. Sensitivity is 15rnJ/cm", contrast is 2.5,
A good pattern with a width of 0.5 μm was obtained without any film loss. (Effects of the Invention) If the photosensitive composition comprising the alkyl-substituted aromatic azide compound and the alkali-soluble polymer compound of the present invention is used,
It is possible to reduce vague loss (of the coating film after exposure and development), and it is possible to form a high-resolution pattern. The cross-sectional shape of the formed pattern is substantially vertical. Furthermore, since the photosensitive composition of the present invention is a negative resist, it has the advantage that the amount of light that reaches the underlying substrate during exposure is small, and the influence of reflection from the substrate is small. Furthermore, when a polymer compound having a benzene ring is used as the polymer compound in the photosensitive composition of the present invention, it exhibits sufficient dry etching resistance and is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the photosensitivity characteristics of resist films made of photosensitive compositions according to examples of the present invention and conventional examples. Figure 1 4 Likelihood [^;/-]

Claims (1)

[Claims] 1. The following general formula (1), ▲ includes mathematical formulas, chemical formulas, tables, etc. ▼... (1) (In the formula, at least one of X and Y has 3 to 7 carbon atoms. 1. A negative photosensitive composition comprising an aromatic azide compound represented by (representing a group consisting of a straight or branched hydrocarbon chain having a straight or branched hydrocarbon chain, and the remainder representing H) and an alkali-soluble polymer compound. 2. A claim characterized in that at least one of X and Y of the aromatic azide compound represented by the above general formula (1) consists of a straight or branched hydrocarbon chain having 3 to 5 carbon atoms. The photosensitive composition according to item 1. 3. Claims 1 to 2, wherein the polymer compound is at least one polymer compound selected from the group consisting of condensation reaction products of phenols and formaldehyde and hydroxystyrene polymers. The photosensitive composition according to any one of the above. 4. A step of coating a photosensitive composition containing an aromatic azide compound represented by the general formula (1) and an alkali-soluble polymer compound on a substrate to form a coating film, as described in claim 1; A pattern forming method comprising the step of forming a predetermined pattern on a film. 5. At least one of X and Y of the aromatic azide compound represented by the above general formula (1) is an aromatic azide compound consisting of a straight or branched hydrocarbon chain having 3 to 5 carbon atoms. The pattern forming method according to claim 4. 6. Claims 4 to 5, wherein the polymer compound is at least one polymer compound selected from the group consisting of condensation reaction products of phenols and formaldehyde and hydroxystyrene polymers. Any of the pattern forming methods described above.